The present invention relates to a shift lock mechanism of an automotive column automatic transmission (AT) shift lever device.
A column AT shift lever device is a device wherein a shift lever is mounted near a column shaft. In a widely employed construction, at the time of a shift operation, for example, from the parking position to a drive position, a select button provided in a shift knob is pressed so that the engagement between a detent plate and a detent member is released by operation of a select rod or a select cable, thereby permitting shift operations to proceed.
Column AT shift levers of this type incorporate a shift lock mechanism. The shift lock mechanism is a multi-purpose safety device which prevents a car from jolting into motion by requiring the driver to step on the brake pedal before engaging the car into gear, other than the park position, and also prevents removal of the key unless the column shift is returned to the park position to prevent the car from rolling. The lock cylinder has a LOCK position when inserting/removing a key, and an ACC position to start and drive the car.
As a shift lock mechanism described above, a solenoid type mechanism has been conventionally employed, wherein movement of the brake pedal is detected by a switch, and when the brake pedal is depressed, a solenoid is operated to release the shift lock. However, such solenoid type shift lock mechanisms have drawbacks in that a solenoid adds to the total weight, and there is a need to provide a mechanical emergency override in case of a problem in the electrical system. Thus, the entire construction becomes complicated and costly.